Lecture 2: Climate Flashcards
What causes the daily periodicity on Earth (day vs. night)?
the rotation of the Earth around its axis
What causes the lunar cycles (tides)?
The revolution of the moon around the Earth
How long are the lunar cycles?
~27 days
What causes seasonal patterns by hemisphere?
the revolution of the Earth around the sun combined with the tilted axis of the earth
What is the degree of the Earth’s tilted axis?
23.5 degrees
Define climate
the long term average patterns of temperature, humidity, precipitation, wind, atmosphere pressure, etc.
What scales can climate be described at?
local, regional or global
Define weather
A combination of temperature, humidity, precipitation, wind, atmospheric pressure, etc. in a particular time or place
What are the 4 major components of climate?
- electromagnetic radiation (light and temperature)
- winds
- ocean currents
- precipitation
Approximately how much of the incoming solar radiation reaches the Earth’s surface?
~ 51%
If 100% of solar radiation are incoming to Earth, what % of SR is absorbed by clouds and the atmosphere?
~19%
If 100% of solar radiation are incoming to Earth, what % is reflected back to space by clouds and the atmosphere?
~30%
Of the ~51% SR that that reaches the earth’s surface, what % heats land and oceans?
What happens to the remaining % of SR?
~21%
the remaining ~30% is either used up in evaporation or thermal energy
Of the ~51% SR that that reaches the earth’s surface, what % evaporates water off the surface of the Earth?
~23%
Of the ~51% SR that that reaches the earth’s surface, what % is used up to heat air next to the surface (aka thermals)
~7%
What % of SR is radiated by the Earth’s surface?
117%
What is the name of the effect/process that re-radiates the SR radiated by the Earth’s surface back to the Earth in order to maintain a hospitable temperature?
What % SR does it trap and what % does it re-radiate back to Earth?
The Greenhouse Effect
traps 111%
re-radiates 96%
What % SR is lost to space after it has been radiated from the Earth?
~6%
What type of SR is radiated back to Earth as a result of the Greenhouse Effect?
Thermal radiation (longwave)
What type of radiation is directly from the sun?
Solar radiation (shortwave)
What are the overall inputs of SR for Earth?
51 units from sun reaches Earth + 96 units radiated back from GHE = 147 units
All inputs are SR/shortwave
What are the overall outputs of SR for Earth?
30 units SR to space + 117 to atmosphere = 147 units
All outputs are thermal radiation/longwave
Does the approximate amount of SR that reaches the Earth’s surface balance the amount that leaves?
Yes, about 147 units gained and lost
Describe the Greenhouse Effect
When SR reaches the surface, the radiation is converted into lower-energy infrared radiation which is radiated from earth and absorbed by the GHG in the atmosphere (ex. water vapour, CO2, methane).
This lower energy radiation is re-radiated back to Earth
What is the significance of the Greenhouse Effect?
The earth loses so much thermal radiation (~117%) so the GHE traps and re-radiates most of it back to the Earth in order to maintain a temperature that is conducive to life
T or F: most of the heat radiated by the Earth is radiated back by the atmosphere?
True
What are the two kinds of electromagnetic radiation?
- solar radiation
2. thermal radiation
What are the wavelengths and types of solar radiation?
Ultraviolet light, visible light, and near infrared light
Wavelengths: 100nm-5000nm
What wavelength range is visible light in?
400nm-700nm
Describe visible light
Solar radiation that is within the visible range for humans and the region that plants use for photosynthesis
What does PAR stand for?
Photosynthetically Active Region
Describe UV radiation?
Solar radiation that is harmful and can cause mutations
Bees and other pollinators can see UV radiation but humans cannot
What are the wavelengths and types of thermal radiation?
far infrared
wavelengths: 5000-100,000nm
Describe thermal radiation
the long-wave radiation off the surface of the earth that is also radiated back from the atmosphere as part of the GH effect
Give an example of how animals can use thermal radiation to their advantage
Pit vipers can sense thermal radiation to sense the heat signatures of their prey
Define albedo
the fraction of solar radiation reflected by an object
it also depends on the properties of the surface
Describe the albedo effect on dark-coloured surfaces
Dark colours absorb more SR and heat up
Describe the albedo effect on light-coloured surfaces
Light colours reflect more SR and remain cooler in temperature
T or F: albedo effect has little impact on climate
FALSE. It has a major impact on climate
If a surface has low albedo it is…
darker in colour because the fraction of light it will reflect is low
If a surface has high albedo it is…
lighter in colour because the fraction of light it will reflect is high
What albedo level does fresh snow have?
HIGH - 80-90%
What albedo level does sea ice have?
HIGH - 50-90%
What albedo level does water have?
10-60%
What albedo level do forests have?
LOW - 10-20%
What albedo level do croplands/grasslands have?
LOW - 10-25%
What albedo level does asphalt have?
SUPER LOW - 5-10%
How does albedo have a compounding climatic effect on the North and South Poles
When the snow melts, the exposed ground will absorb more sunlight/heat up so as global temperatures increase, more snow melts more frequently so there are longer periods of exposed ground with LOW albedo making the temperatures rise even higher
How does the albedo effect have a role in developing rural areas into urban areas
As we remove areas with higher albedo levels and put in more asphalt with very low levels of albedo, we are warming the area
T or F: temperature remains constant regardless of the latitude
FALSE. it varies with latitude
What 2 things does the amount of SR that reaches Earth’s surface depend on?
- The travel distance through Earth’s atmosphere
2. the angle of incidence
What is the angle of incidence?
the angle at which the SR/light hits the earth’s surface
What characteristic of Earth’s rotation affects the angle of incidence and distance of travel through the atmosphere?
the central axis of Earth being tilted 23.5 degrees
What kind of angle does solar radiation hit the earth at higher latitudes? What effect does this have on temperature?
An oblique angle
The light is spread across more surface area so it is less intense and therefore not as warm
What kind of angle does solar radiation hit the earth at the equator? What effect does this have on temperature?
a right angle
The light is spread across a smaller surface area and hits the surface directly so SR is more intense and temperatures are warmer
Does SR have to travel a further or shorter distance through the atmosphere to reach the Earth’s surface at higher latitudes compared to the equator?
How does this effect temperature?
Has to travel further to reach higher latitudes
The longer the SR is moving through the atmosphere, the more opportunity there is for it be absorbed or reflected before reaching the surface
Define the solar equator
the latitude that receives the most direct rays of sun at any time of the year
T or F: the solar equator is always at the actual equator
FALSE. only twice a year is it at the actual equator
Where is the solar equator?
it shifts between 23.5 degrees north and 23.5 degrees south during earth’s yearly revolution around the sun
Temperature and day length vary seasonally due to the…
position of the solar equator
What time(s) of the year will the solar equator be at the actual equator?
the March and September equinoxes
When there is equal day lengths
What time(s) of the year will the solar equator be at the 23.5 degree NORTH latitude?
June solstice
What occurs on the June solstice in the northern and southern hemispheres?
The tilt of the Earth’s axis is pushing the northern hemisphere closer to the sun, so the solar equator is at 23.5 D. North
The June solstice is when the Northern Hemisphere will have the longest day of the year
South: shortest day of year, furthest from the sun
What name is given to the solar equator when it is at the 23.5 degree north latitude?
Tropic of Cancer
What time(s) of the year will the solar equator be at the 23.5 degree SOUTH latitude?
December solstice
What occurs on the December solstice in the northern and southern hemispheres?
The tilt of the axis is pushing the southern hemisphere closer to the sun, so the solar equator is at 23.5 degrees south
- the longest day of the year in the southern hemisphere
North: further from the sun, the shortest day of the year
What name is given to the solar equator when it is at the 23.5 degree south latitude?
Tropic of Capricorn
What’s a way to remember the names for the solar equator tropics?
Tropic of Cancer occurs on the June Solstice: zodiac signs for June 21- is CANCER
Tropic of Capricorn occurs on the December solstice: zodiac signs for December 21- is CAPRICORN
Not only does temperature vary with latitude and season, it also varies…
over land and sea
Location within landmass has an effect
- coastal areas tend to be more temperate
What scale of pattern does precipitation have?
global
How are precipitation patterns predicted?
by movement of air masses
Define Hadley Cells
the two circulation cells of air between the equator and 30 degrees N and 30 degrees S latitudes
Describe how Hadley cells work
- Most direct SR hits the surface at the equator and warms the ground and the air
- warm air rises
- as warm air rises, expansion cools it down
- moisture condenses in cool air and falls as rain at the equator
- warm air continues to move towards the poles
- the warm air radiates heat to space and ground
- at 30 d N and S: cold air sinks and as it is sinking, it is heated by compression
- as the air warms, moisture evaporates off the land at 30 d. N and S.
- cool air flows towards equator
- cycle starts over
What is the ITCZ?
Intertropical Convergence Zone
It is at the SOLAR equator (Shifts as the solar equator shifts)
What happens at the ITCZ?
it is the area where the Hadley cells that circulate from the equator to 30 N and 30 S converge
What kind of climates do the latitudes 30 d N and 30 d S experience as a result of Hadley cells?
hot, dry deserts
What kind of climate does the equator and ITCZ experience as a result of Hadley cells?
Hot, moist tropics
Why is there only one distinct wet season at 23.5 degree N and 23.5 degree S during their solstice and the rest of the year is the dry season?
the ITCZ is where the Hadley cells converge (where they will drop all the moisture) and the ITCZ is where the solar equator is
The solar equator and ITCZ will be at 23.5 degrees N on the June solstice
and at 23.5 d S on the December solstice
Why does the equator experience two wet seasons and two dry seasons per year?
Because the solar equator, and therefore the ITCZ (where the Hadley cells converge) is at the equator twice a year during the equinoxes. The other 2 times, it is either 23.5 d N or S.
T or F: landscape topography does not influence rainfall
FALSE
Define rain shadow
A region with dry conditions found on the leeward side of a mountain range as a result of humid winds from the ocean, causing precipitation on the windward side
What occurs on the windward side of a mountain range that is near an ocean or large body of water?
- prevailing winds move warm surface water which warm air will evaporate from across the ocean towards the land
- warm air is pushed up to higher altitudes as it moves up the mountains
- as the warm air rises, it cools and the moisture will condense and fall as rain
resulting in very moist, lush rainforest conditions
What occurs on the leeward side of a mountain range that is near an ocean or large body of water?
- as the warm air cools off and moisture falls as rain on the windward side, what is left to roll over the top of the mountain is very cold and dry air
- as the air moves down in altitude, it will warm up and have a higher moisture holding capacity so it will pull more water off the land through evaporation
resulting in very dry, arid desert conditions
What type of climatic conditions usually occur on the windward side of a coastal mountain range?
moist, lush rainforest
What type of climatic conditions usually occur on the leeward side of a coastal mountain range?
dry, arid, desert conditions
Define the Coriolis effect
the deflection in the pattern of air flow due to differences in the Earth’s rotation speed
T or F: the speed of the earth’s rotation is different at different latitudes
True
Where is the speed of the earth’s rotation the fastest?
at the equator
If an object is moving AWAY from the equator, which direction will it be deflected as a result of the Coriolis effect?
objects and air masses deflect IN THE DIRECTION OF SPIN when moving away from the equator toward the poles
This is because the earth’s rotation is faster at the equator than at the poles
If an object is moving TOWARD the equator, which direction will it be deflected as a result of the Coriolis effect?
objects and air masses deflect in the OPPOSITE direction of spin when moving towards the equator
What are the 3 kinds of major wind currents?
- Westerlies
- NE or SE trade winds
- Doldrums
Where do the Westerlies occur? Which direction do they flow?
high latitudes, from WEST to EAST
Where do the trade winds occur? Which direction do they flow?
Mid latitudes
NE trade winds blow from the North East
SE trade winds blow from the South East
Where do the Doldrums occur? Which direction do they flow?
at the equator
they produce little to no wind
Which direction are winds named for?
the direction they blow FROM
ex. westerlies blow from the WEST
What 3 things cause ocean currents?
- prevailing surface winds (air currents)
- differences in temperature and salinity
- topography of ocean basins
What influences the direction of ocean currents?
the Coriolis effect
What is the name of the big ocean current to know for this course?
Thermohaline Circulation
Describe the Thermohaline Circulation
It is essentially the ‘ocean’s conveyer belt,’ because it connects all major ocean basins on earth
Describe the flow of the Thermohaline Circulation
- warm water flows from the Gulf of Mexico to the North Atlantic (some of it freezes and evaporates)
- the remaining water is left saltier and denser and will sink to the ocean floor
- the cold water travels along the bottom of the ocean connecting the world’s oceans
- eventually, the cold water will rise to the surface and circulate back to the north Atlantic
Describe upwelling
This process occurs when wind currents blow warm surface water away from the coast out to the open ocean
As the winds move the warm water away, they create a vacuum that pulls cold water from the depths to the surface and bringing nutrients along with it to replace the warm water that was removed
What is the function of upwelling?
Everything that dies in the ocean will sink to the bottom so most of the nutrients are out of reach for the photosynthetic organisms that live near the surface
upwelling brings the nutrient rich water to the surface for the photosynthetic organisms
What does ENSO stand for?
El Nino Southern Oscillation
What occurs in ‘normal’ years as opposed to El Nino or La Nina years?
in the southern hemisphere, the atmospheric pressure is low
Usually it is low in Darwin, Australia and high in Tahiti, this allows winds to flow from Tahiti to Darwin along with the Coriolis effect
Normally, eastern trade winds push warm surface water westward away from the coast Peru (allowing regular upwelling to occur)
T or F: winds flow from areas of high pressure to low pressure
True
During an El Nino year, what happens to the atmospheric pressure and winds?
Southern oscillation creates an extreme pressure difference in the opposite direction
HIGH in Darwin and LOW in Tahiti
SO the trade winds will either calm down or reverse and warm surface water will move EASTward TOWARD the coast of Peru preventing upwelling from occurring.
What climatic conditions occur in an El Nino year?
very warm, wet temperatures in North America
What climatic conditions occur in an La Nina year?
abnormal cooling and low precipitation in Eastern tropical Pacific
How does the ENSO impact coastal marine ecosystems?
It prevents the crucial process of upwelling in the oceans. If upwelling does not occur, then nutrients from the depths of the ocean are not cycled back to the surface and the photosynthetic organisms (which are the basis of the community) are unable to acquire the nutrients they need to survive
How does the ENSO impact coastal terrestrial ecosystems?
It creates unusually warm and wet winters, which is abnormal to the ecosystems that generally receive cooler and drier winters.
